1. Field of the Invention
The present invention relates to a method of producing a film-laminated base plate and an apparatus for laminating a base plate with a film layer in a continuous process under a vacuum.
2. Description of the Prior Art
Conventionally, in the process of applying a film such as a filmy photosensitive material layer on a convex-concave surface of a base plate, such as a printed wiring board, there has been a problem that unavoidable clearance spaces remained between the base plate and the film layer. This defect appears to be inherent to the conventional process which is performed under atmospheric pressure. When a film layer is laid on a convex-concave surface such as that of a printed wiring board which has relatively deep circuit relief portions in a high density, the conventional heating and pressurizing lamination method inevitably causes entrainment of air between the joining surfaces resulting in an insufficient contact in the surfaces of the relief portions. The inventors have found that the abovementioned problem is solved by performing the lamination process under a vacuum.